1. Field of the Invention
This invention relates to a point-of-sale (POS) systems, and particularly to a POS systems that are capable of detecting a failure or an imminent failure.
2. Description of Background
Computer systems that accept data streams generated by operating a stylus are commonplace. A stylus based user interface generally comprises a pen (called a stylus) and a digitizing tablet. The use of stylus-based user interfaces is being driven by the general trend toward more natural user interfaces utilizing handwriting and freehand drawing.
In many application programs, stylus-based user interfaces are superior to keyboards as a means for entering data. Such is the case, for instance, when a user of the computer has only one hand available for data entry. Other cases include, but are not limited to, those in which a keyboard would add too much bulk or weight to a data processing system designed to be highly portable or the case of a system designed for operation by a user who does not know how to or is physically unable to type.
However, an input stream from a stylus-based user interface is more difficult for the system to interpret and makes the development of stylus-based application programs very complex. The input stream of a keyboard or mouse unambiguously reflects a user's intention, that is, to select a particular keyboard key or mouse button. The application program may or may not be able to respond meaningfully to that particular input data.
The stylus-based user interface, on the other hand, functions as a source of both character data (such as text, function keys and editing commands) and gesture data (i.e., mouse data such as pointing and selecting). Regardless of which of these two types of data the user intends to enter, the input data stream of the stylus-based user interface consists of a series of x-y coordinate pairs (called x-y data) that describe the locus of the stylus as the user operates it. Stroke data are generated from the x-y data. Stroke data represent strokes, which are sequences of the x-y coordinate pairs delimited by a pen-down event and a pen-up event. A pen-down event occurs when the stylus first touches the digitizing pad. A pen-up event occurs when the stylus next leaves the digitizing pad.
Some application programs, such as a sketching application or a signature capture application program, are required to deal directly with these strokes. Most application programs, however, are required only to deal with the character data represented by the strokes. Accordingly, stroke data is interpreted before an application program can process it. The interpretation may involve classifying the stroke data as gesture or character data, and/or converting them to character data. Accordingly, interpreting stroke data is a complex process, which generally requires much programmer time to implement, and much Central Processing Unit (CPU) to run.
In addition, in self-service environments it is important that Point of Service (POS) hardware be capable of detecting its failure or imminent failure. Signature capture devices do not appear to have any means of providing such information. Thus, it is well known that POS systems such as signature capture devices do not provide for an automatic failure detection mechanism. Therefore, it is desired to develop a method for detecting irregular flaws when a user uses a signature capture device.